Gas-burning wall heater



July 8, 1952 J. H.-Ho|.'|.|NGswoRTH ErAL 2,602,441

GAS-BURNING WALL. HEATER 2 SHEETS-HEM 1 Filed April 23, 1951 F/GZ 'INVENTORJ.'

./oH/v muwssmrff, BY KARL L. 5505,

/1 TT OR/VEY J. H. HOLLINGSWORTH ETAL July 8, 1952 GAS-BURNING WALL.HEATER 2 SHEETS-SHEET 2 Filed April 23, 1951 l-'LUE HEIGHT ABOVE DRAFTHOOD- FT.

/NNER'WALL I TEMPERATURE TA kE/v HERE IN VEN TORS. JOHN H. HOLLINGSWORTHKARL L BEDELL ATTORNEY are disadvantages.

Patented July 8, 1952 4 UNITED STATES' PATENT OFFICE GAS-BURNING WALLHEATER .lohn H. Hollingsworth, Altadena, and Karl L. Bedell, Pasadena,Calif., assignors .toi Holly Manufacturing Company, Pasadena, Calif., a

y corporation of Californiar Appiication April 23, 1951, serial No.222,500

in areas Where gaseous fuel is cheap. They offer a number of advantages.They are relatively inexpensive to build and simple to install.` If

properly constructed',` say in accordance with the standards oftheAmerican Gas Association, they are safe. They are relativelyeconomical in operation and'heat space quickly-an advantage in climateswhere the mornings or nights are cool but the days are relatively warm.But there Conventional wall heaters tend to produce high walltemperatures Vabove 'the heater and adjacent the flue, and thisis soeven when 4the installation meets the requirements of the UnderwritersLaboratoriesA and presents no re hazard. High wall temperatures,

even in the absence'qof nre hazard inthe wall,

vevidence a heat loss in the'flue." Even when this `loss is notYexcessive, the customer reaction is lpoor. temperature-by bleeding airinto the flue, the

If an= effort is made to lower the wall resulting heat loss, ythoughapparently lower, may

.actually be increased.

heated circulates. A tall hollow radiator/is set inthe box and is redinside with rgaseous fuel. Air rising Vthrough the box is heated by theradiator :and'passes out into the room. ,Heat not transferred by the"radiator' remains in the 'gaseous= products of combustionv and/,iswasted up the flue .connectedtothejt'opy o f the radiator'.

A draft hood or diverter maybe 'connected in the fluejabove theradiator. Thisl hasr a relief outlet, usually* into the room throughthejbox in which the radiator is disposed, and serves-several purposes'a-If'the flue should becomechoked, the flame in the radiator will not beblownout andthe" gaseous combustion products will escape through therelief outlet. If- 'a down draft 'should develop in theflue, the sameresults will follow. On the' contrary, if an. excessive up-draft shouldexist due to an excessively; high ,chimney lorv flue, or should developtemporarily due to a hghWinLd,

vso

'increased lossof heatup the flue.

2 air from the room will be sucked into the flue from the relief outletand the relief outlet-will thus prevent the excessive draft frominterfering with proper combustion in the radiator.

For'safetys sake, a wall heater of the type described is so designedthat, even with-onlylthe four foot flue employed in American GasAssociation tests, a considerable volume of warm air will passcontinuously into the flue through the relief outlet froml the room.WithV the taller flues customarily used veven in one story houses,thisvolume is increased. A two story iiue still further increases thedraft and the amount of warmair lost up` the chimney or flue." The warmairsucked intothe ue through the draft diverter thus represents arconstant andsubs'tantial heatv loss, which increases as draft isincreased.A

As indicated at the outset,rthe flue-above vthe radiator tends lto heatthe wall in which4v it is enclosed. The more the fuel burned, the hotterthe-flue' gasV-thehotter the wall and the greater In cold'weather,

ously. hot due tothe large amount of fuelv burned, and this hot wallcondition is accompanied.' by If van attempt is made tot reduce the walltemperature by bleedinggin air. from the draft diverter, a. lower walltemperature is obtained'but only at the expense of a still furtherdecrease in heating eiciency.

As avresult"` of our investigations we have de'- velopeda wall heaterwhich t" (a)` eliminates high wall temperature; .l

(b) does so without decreasing heating efficiency and in fact with asubstantial increase in heating efficiency;

' .(c) increases air circulation in the room in which-the heater isinstalled; and

(d) v can be installed with flues which normally would produce excessivedraft, without deleterious effectupon heating'efficiency, so'that the`heater is adaptable tofa greater variety of draft conditions thanconventional'heaters While keeping heating efliciency high. v n 9' y Inaccordance with our invention, a Wallheater is Vconstructed in twosections. The lowerA section' comprises a Vgas-firedy hollow; radiatordisposed in a box in the wall yof a room immediately abovelfloor level;The vupper section is likewise n af'rfadiatorfjdisposed .in a box inthe, wall "and placed above fthe" kfirst radiator but mainly below the:ceiling. Ther two radiators' are connected kin series. Gas` is burned inairin the first radiator and the resultingfflue. gases rise v.through thextending walls of the box. Box'andgenclosed radiatorare thus installedtogether inthe-wall, .preferably with an insulating space in thezA walloutside the box.

of equal height outside.

V,flue 1 temperature.

3 second radiator and are discharged into a flue connected to its top.

No damper or the like for ccnstricting the flow of the flue gas throughthe two radiators is provided, and a draft diverter is connected 5'between the two radiators, instead of at the ue, as is customary. Thisdiverten has its yreliei` opening into-the room, preferably through thebox in which the lower radiator is placed.

Air to be heated is admitted into the lower portion of the box from theroorn, r ises along the lower radiator and is discharged intothe room atthe top of the box. Airi from floonlevel in the room is passed upwardthrough a= separate conduit into the bottom oftheupperfbox in which thesecond radiator is disposed. Preferably this separate conduit isdisposed aroundthe sides or back or both of the lower box. Airintroduced by the conduit into the upper box riseslalong the secondradiator and is discharged into the room through an outlet-inthe upperboxnear the Ceilingf The secondi radiator preferably is formed .-asy aunit With its .bQX,..a.r1d spacedfrom theupwardiv signed so that anormaldraft with avery short flue will barely cause air tc be. drawn intor theAsystem through -the draft-.hood and so thatincrease in chimney eectdoes not increase dilu- '35 tion through the draft hood ,to vasubstantial degree.

The 'reasons for the structure just described and the results thereofare as follows:

Draft is Whattends to. make gas :move upward 40 through a flue and isthe `result.;of a pressure dierentiaL i. e. the difference in. thedensity. of

the column of gasin'the flue andi a likecolumn Hence i .theoreticallyavailable draft is a function offlueheight and Although ithe;theoretically available .draft is a measure `ofgstatic condition andispnever fully obtained dueto frictionallosses in.v the fluep the actualdraft.l at any flue ytemperatureis still jcloselyrelated to the-.flueheight andY any increase inthatiheight; willcausethe flow of gas toincrease .until thetotalenergy.loss of the systemedualsithetheoretically.;available draft. :The function o'f theIdraitf.hoodiorrdiverter;in the device of the inventionis..,torstabilizeiidraft .conditions existing4 within the lower radiatorvregardless of variations in draft :conditions .above it. This isaocomnlished. vicy-nlacingsuitable .bafiiesinthe. .draft hood (soesto.direct.. the.f10w of...gas properly)- and .by the vent which, providesa. Sollre .0f lfelef' .air- The; qlafhhoodfes, :E913 Qontrol ,the draftaction .established Within ,the flue but only its effect on .thecombustionzone in the lower radiator. j n 'v Draftin a flue may be`controlled satisfat'forly and safely in Vmany instances by. a damper."They have been usedffor' many .years `.inthe Aiiue's of fireplaces.`VAdjustable dempers, however', are. not satisfactory the fluefof fagas-bliifliidef, because of the'possibility'offaspfhyxatio Re ognizedtesting agencies and'gOl/.Brlm'eil'b'ds condemn them, and Athey jarejforbidden'jin Vmany places V by building codes andordinances.

tends toward a constant value.

in dilution throughthe draft hood.

tially proportional to the velocity of such flow. But under conditionsof turbulent ow resistance to ow is more nearly proportional to thesquare .of the velocity. Consequently, if the horizontal cross sectionof the upper radiator is constricted. preferably until turbulent flowconditions obtain, alarge increase in draftfsayduefto a tall chimney ora high wind, Willnhave a minimum effect at the draft hood below theradiator. Hence the suction at the relief opening of the draft diverterIf the system is designed so that it barely draws in air throughlportioniif-theflue height is increased. Loss of even if the wall heateris installed with a flue system that creates excessive draft, andheating efficiency is thereby improved.

In other --words,;the cross section offthepsecond radiator is chosensogthatias a ,conduit it v.willfiust Ahandle the maximum products ofcombustion @to Vbe conducted inA theyirstradiator,Y with scarcely anydilution throughthe draft hood. -Withzsuch y a design, amarkedfincreasein draft will produce a minimum increase; in draftxatthe` .base .-.ofethe second radiator, and hence @minimums-increase ByV.drawing the L4cold- .air zup. around the. .sides or the back, or both,ofthe lower box, ,the-,neighkboring-wall surfaces are cooled andmorefuel may ibe'burned safely without attaining excessiye/lowerwallitemperatures. HenceL the-heating :ca-

pacity lof the apparatusis increased. Moreover, the air for theupper-'heat exchange..becauseieit is drawn from a low #level has alowertemperature. so that the h ea'mtransfer` from ,thejupper radiator. isincreased. In this vway.;.the4 amount of heat; imparted tojthe airlpassed .through :the upper lbox (i. e. the conduit Varound the yupperlradiator) is increased, with a Aresulting :improve- -rnent Ain over-allheatingefhciency. Thirdx the use of` cold. or low level.; air -asfeed tothe secondary heat exchanger 'makes it; possible safely tov v,en-

case this secondary-heat.exchanger .vin, a;- com .-bustible ywall.Fourth; the structurezof the 4 ,i-nventionfis such thatvv the hotterairisfbroughtout intothe room at an intermediate level whileioooler but.still-warm air. is introduced int0;'jthe1. upp1` part of the room neartheceiling, thus reducing stratification Yand. increasing aircirculation.. in

vThe over-all-effect Y of they application-ofithe invention-is striking.AAIn actual -tests fit-raised thermalefficiency by -more-than 10% fincreased the-volume of warm: air circulated inthe-room byvapproximately 25%V and-reduced Vupperevvall temperature from about 150'F.'above'room-temperatureto about F. above room temperature. At thesameA time, thecost ofthe secondary heat exchanger employedwas .butlittle .moreLthanltliat of the I iuesection whichlitreplaced.

The foregoing and other aspects. ofour-invention .will .be understoodImore, thoroughly `nfthe Hennef-.the fouowingffidetaileddeseriptmntakenirriconiunction with. fthe..aceompanyingfdrawing ini-Which! Y y :Fia151s; a. diagrammatcgsectidnalr.,elevationfof a .presently preferredembodiment;ofi-theifwall heater ofour invention; i..

Vrlligs.l 2; Brand.; 4. iarencross :sectionsitaken reispectivelymalong,'.theli-nese Sis-3,: and 0f;ifFig,.1';f e r 1 311i;

`Fig. 6 .is a graph of the results of tests con ducted to determine therelative heating efliciency of conventional wall' heaters and that ofthe invention for various chimney or flue heights, thermal inputbeingthe same in all cases; and

Fig. 7. is a, plot of wall temperatures against flue-temperaturesobtained in testing wall heaters ofthe invention, as compared withsimilar plots for conventional 'heaters equipped inv one case with anaccepted composition flue (Portland cement-asbestos) and in the otherwith a standard double wall metal flue.

Figs. land show a wall heater set in a wall Il of a room and having twoseparate chambers I3, |4, one disposedabove and oiset centrally of theother.v y

The lowervcharmber I3 isa tall shallow box or jacket, setuprightfin arecess of the wall. The box is rectangular in section both horizontallyand vertically. Y A hollow radiator or heat exchanger I5 preferably madeof a black surfaced metal and ofv considerably smaller horizontal crosssectionthan .the jacket, is disposed centrally of Athe jacket in anupright position. rIfhereis an inner annular air space ll between thejacket and radiator, and a second vouter annular air space I8- betweenthe jacket and an encompassing` heat vconductive shell I9.v The shell isbox shaped and ofgreater cross sectional dimensions thanl the Vjacketwhich is disposed centrally within it` The shell has a front side 2lexposed to the `room and an opposite rear side 22 spaced from-the backwall 23 of the recess, leaving an air space Ior conduit 24 behind it.

.Neither the jacket nor radiator extends to the b ottom of the shellasshown in Fig. 1. However, the jacket could extend -to the bottom ifitwere provided with a series of ports for circulation of ainy v e Y Agas burner 21 at the bottom of the shell is so placed that it projectsAflaming gases into( y theopen bottom ofthe radiator.

.The front of the shellis provided with two spaced sets of louvers 29,30, V1r't'elatively 'cold air is drawn into the chamber through thelower louvers, near the 'floonand discharged asrheated air to the roomthrough the upper set of louvers, adjacent the top of the shell andabout midway up the wall. The air may rise through either the annularspace Il dei-med by the heat exchanger and jacket or between the jacketand the shell in the space IB or between'the shell and the wall in thespace 2li, with the combustion gases ascending through the interior ofthe hollow heat exchanger. The lower jacket `or chamber does not extendto the top ofthe shell and `hence hot air rising-inthe jacket may escapeinto the Vshell, and thence to the room through7 the upper set oflouvers. The outer vannular air-'space-Zl-serves primarily asan'i'nsulating chamber, protecting the rear wall of the recess and thesides of the shell from excessive heat. The gas burner is provided witha Ythe middleklouver; K

Cold air, say at about 70 F., passes up from constructed of a darksurfaced heat radiating metal. VSave forthe lower .end which extends fintov the recess. the second heat exchanger is completely enclosed inthe upper wall in an up.- right position.

. The second box or jacket Ill is completely en closed in the upper wallyand is centrally-disposed around the second radiator to which. it isattached. The second jacket extends from the top of the recess to theceiling of the room, forming two annular air spaces, a rst air spaceY dl(see Figs. 1 and 2) between the jacketv and the radiator and a secondair space 42 between the jacket and the interior surfaces of the Wall'.The air space 24 defined by the outer wallof the shell andthe innersurface of the back Wall of the recess opens into the air space 4I.between the upper jacket and second radiator.

Air heated by the upper radiator and rising through the air space dl isdischarged .into the.'

room through a. lateral duct 44 connecting-the jacket to the louvers`cfa register d5 set flush in the wall near the ceiling of the room;`The outer air space d2 between the jacket `and the interior surfacesofthe wall aids in. preventing excessive heating ofthe wall. f

As shown plainly in Fig. 2, 4the* chamber and the radiator .of thesecondary heat exchanger are of flattened cross section, both beingconsiderably'shorter transverse to the Wall than parallel to the wall.,Conveniently, both radiator and shell yor jacket rare made of opposedsheet steel halves welded together along lapped flanges. The flattenedsection of the exchanger is useful in that it permits large heatexchangecapacity to be installed in a relatively thin` wall. The radiator issubstantially smaller in cross section .than the lower or primaryradiator.

The operation of the. apparatus described in conjunctionwith thedrawings is as follows:

Gas is burned in the lower radiator. This gas may attain a temperatureadjacent the burner.

as high as 2000" F. The hot gases of combuse tion rise through ftheradiator and the draft hood into the second radiator and thence areexhausted to atmosphere. Thejhot'gases in rise ing through the lowerradiator decrease in tem`n peratureto about 650 F. This temperature is.

reduced slightly in the drafthood.. The'. temperature of the gasesvleavingthe upper end of the sec. ond radiator is. about 450 F. Airenters the space' in the lower heatexchanger around the radiator at oorlevel and'at a temperature of aboutsayl l 70? F. `In passing up throughthe jackets in. the lower exchanger the temperature of this air isincreased to about' 375 F., at which tem-v perature it is dischargedinto the room through the iloor level to the box surrounding lthe secondradiator through the wall and in passing to the upperlouver (of "thesecond 'heat exchanger) adjacent the ceiling attains a temperature ofF., at which temperature it is discharged.

Extensive tests have been made to determine quantitatively the effect ofthe heater of the invention on heating efliciencyand wall temperature.These results are summarized in Figs. 6 and '7 and there compared withheating efciency and wall temperatures observed with f conventional wallheaters of high quality under like conditions.

Fig. 6 illustrates the effect of draft (chimney action) upon heatingeliciency with conventional Wall heaters and those `of the invention.The

iueheight:forv heater-zA, flwhich.'y represents thai average.; valuesobtained .in actual. tests :with: La#

number of. makesof heaters disposedL inaA wall,...

with a suitable draft hood at thettor'v.A of :the 1.

heaterrand". about half-.way up the wall: in .each

casefatwhich point. it .was connected -to a stands...- lard flue.section; .the :height aof.A which.' iwasii'- i .'-L'i creasedas shownzinorder-tofincrease thedraftz: stepwise, The linermarked: HeatenB isv a.plot-l ofa'ctuall eiiicencies .obtainedfwith the heater;

illustrated; inl; Figs.. 1. toY .5, as fwith. .the .convenz-ptionaluflue section.` immediately. .alcove the: draftv i hoodoffiheater. A replaced .bya secondaryheatV exchanger.. The radiatorl ofthis secondgtexff. changer was' of uniform''.lout"small.horizontalAcross' section so'V thatwiththe. shortestflue height,.

the draft hooctmbarely..drewv air. '.LBotlnheaters.

A..S.and B'. burned iuel'r. equivalenti to';255,000 B...'t.. u./.hr..

Figz shows invention.. is superior to. the. conventional i gas= firedwall-'heaters irrespective.` of iiueheightzandr. that asfue heightanddraft are vincreased'.the'- superiority of. ourv heaterbecomesnmorexmarked'. Stated in another way, the. heater: of .theinvent-v tion.. has: a high. thermal leiciency which decreases on'lyslightly' asY draft: increases; whereas theconventionaliheater has a;lower .eiciency tof.`

comes sharply Worsesas. flue height is increased.,` Fig.' 7 illustratesthe decrease'in wa'l'lltempera; x

start'wth. and" this initial .lower efficiency. he.;

ture; -in the: neighborhood. ofiA a "wall .heater brought about. by theinvention; In .the figure,v nue temperature isplottedagainstupper'vwalli. temperature'. for- (1). a conventionaliwallheater`extending about'halfway up'the wal'lricf; a room;

with a drafthoodn at th'etop.. and aA standard:

composition flue of cement and asbestos. in the wall above'it; (2) the;same conventional heater' withv the" same :draft'hood: but.. employing.ia standardidou-ble .wallfmetalueL in' the; Wall; and. (3).l theheaterof the. invention; similar tothe;

other .two .heaters 'except that .ther-flue sections'.

were replaced'by a secondaryheat .exchanger `in thewallifedwith. airfromioor level and. dis-:

charging at ceilingrleveL. asV illustrated. in

Figs

1i toff5.

Irrespectiveof flue temperature,- wall tempera tures with the. apparatusof: theinvention are.'

consistently. lower than .those obtaining when conventionalheaterswith-either of the usual: nue i typesare'used. This. meansthatfin 'times' of verycold i .weatherywh'enn the demand is high, VtheVheaterofztheuinvention maybev called upon to" burn'. a great fuel *load*safely; something. that cannot Lbe said of theotherfheaterss- Itfalsof.means that under normal conditions, no annoy.;v

ingf-ffhot wall'. conditions are'obtained.

Wesclaimi` 1. In a. wall. heater -forI burning gas; thecomf binationwhich'. comprises aV first box@ adaptedfto plainly.. that. the.. heater..of the.

belmountedn.aiwallofl'a; roomfto extendl'upward therein from a levelnear the floor of the .roomv to: va= level -part way-to fthe ceiling; afirst l'hollow radiator mounted in. the-'box and: spaced -fromtne-L-walls-thereof, meanslfo'r burning .fuel in thesrstis radiator; .means.connected-to 'the/lower' portion.l of the firstfbox `for'.introducingair thereintof near the -iloorv4 of the room, means?. connected.' to

thefupper portion Iof fthe rst box. for.' discharge ing-.airintothe'roomfrom the `box-near itstopgz asecond' box'. adaptedtombe-'mountedrrin the wall.. above the:y rst' box` to: extend ffromalevel-"justfv above4 the 'first hoxfto a level' near'fthe'xceilling...a.

second hollow radiator disposed-fin the 's'econdib'oxr` and spaced'fromvthe-walls thereof, the horizontal cross section c'ffthesecond-radiator? being sub*-` stantially' "smaller-'thanthat' of the.rstlrradiator,` 'l means connected with the upper portion-f otr-the.-Z

secondA box' forA discharging tairV from the' vsecond radiator'.

2. Apparatusaccording Ato claim l providedwithv a. baiiie`-"disposedvintheA first' box"kzfehindfthe*- rst radiator andspacedfrom"thefradiator and'.

alsor Vfrom the rearA wall* offthe' box. Y

3. Apparatus'accordingrv to clai'mfl providedwitha baiiie'disposed'inthe-"rst'lbox" behindthev rst radiator and spacedl from 'the radiatorand?r also" from the 'rear' wall' ofithefbox to provide fa conduitbetween :the rear wall" of thel box 'andthe hailie,v said conduit beingopeneat VtheloottomL andv also at" the topandincommunication-'atlthectopiJ with` the'interior 'of lthe rst box". f

. 4. Apparatus according to claim 1 in whichfthey secondn radiator iscomposed y of a Ashallow-2front member and va shallow-"rear member.VA

5. Apparatus according toclaim l" in which-the? secondv box is composedoffa shallow frontv member anda shallow rear'member.=-

Joint 'rrPHQmNGsM/fonmrf KARLLBEDELB. Y

REFERENCES; CIT ED 'Iheffollowingf` references are of .record inthe..`ilefof this .ipa-tent:`

UNITED;` STATES.' PATENTS' Number: Name Date.:

1,361,389r i McLeod. .Dec. .7, 1920: 1,698,775 Traut'.- *Jan.l5-,-.1929.

